Recently, a technique for extracting a potential of a support substrate of an SOI substrate from a surface of the SOI substrate has been proposed.
One example of a semiconductor device includes a semiconductor substrate, a buried insulation film made of SiO2 and formed on the semiconductor substrate, a semiconductor film made of Si and formed on the buried insulation film, a trench isolation surrounding a partial region of the semiconductor film, and a substrate potential contact formed within a region surrounded by the trench isolation and connected to the semiconductor substrate through the semiconductor film and the buried insulation film.
Another example of a semiconductor device includes an SOI (Silicon On Insulator) substrate, on which an n type silicon support substrate, a BOX (Buried Oxide) layer made of SiO2, and an n type silicon SOI layer are stacked in this order, a trench isolation partitioning a substrate potential contact region, a substrate potential contact formed in the substrate potential contact region and connected to the support substrate through the SOI layer and the BOX layer, and an n type well formed in an upper portion of the SOI layer within the substrate potential contact region.